Device and system for improved imaging in nuclear medicine and mammography

ABSTRACT

A method and apparatus for detecting radiation including x-ray, gamma ray, and particle radiation for radiographic imaging, and nuclear medicine and x-ray mammography in particular, and material composition analysis are described. A detection system employs fixed or configurable arrays of one or more detector modules comprising detector arrays which may be electronically manipulated through a computer system. The detection system, by providing the ability for electronic manipulation, permits adaptive imaging. Detector array configurations include familiar geometries, including slit, slot, plane, open box, and ring configurations, and customized configurations, including wearable detector arrays, that are customized to the shape of the patient. Conventional, such as attenuating, rigid geometry, and unconventional collimators, such as x-ray optic, configurable, Compton scatter modules, can be selectively employed with detector modules and radiation sources. The components of the imaging chain can be calibrated or corrected using processes of the invention. X-ray mammography and scintimammography are enhanced by utilizing sectional compression and related imaging techniques.

FIELD OF THE INVENTION

[0001] This invention relates to an improved system for radiographicimaging and material analysis and more specifically for nuclear medicineand mammography imaging.

BACKGROUND OF THE INVENTION

[0002] Two general imaging problems in radiology involve thedetermination of a radiation source distribution and/or the effect of afilter, in this case a patient, on the radiation source distribution.Consider the field of nuclear medicine where the radiation source orother radionuclide distribution emits photons or positrons, Image dataacquisition in nuclear medicine presents several challenges in additionto constraints imposed by finite acquisition times and patient exposurerestrictions. Most photon energies that are of interest in nuclearmedicine are higher than the typical photon energies employed indiagnostic x-ray radiography. In particular, Positron EmissionTomography (PET) involves the detection of pairs of very high energyphotons due to annihilation events. Unfortunately, the photon radiationsource, such as a radionuclide, used in nuclear medicine is notdirectional and the source distribution within the body is not preciselyknown.

[0003] Photons that escape the body may be scattered, altering theirenergies and/or direction vectors. It is desirable for many applicationsto discriminate against scatter radiation reaching the detector based onenergy and/or direction. It may also be desirable to only detectradiation with a specific direction vector, since many detection systemspossess poor directional discrimination capability and have finiteresponse times within which to detect events, thereby limiting detectionrates. Thus detection systems used in nuclear medicine such as Gammacameras or PET scanners often employ conventional, such as attenuatingor rigid geometry, focused or unfocused collimators, often referred toas grids or grid collimators, to help define the direction vectors of adetected photons. The direction vectors and energies of non-scatteredphotons are well-defined. Unfortunately, the emission of photons fromthe source distribution is non-directional and the radiation sourcedistribution itself is typically not well-defined. A Compton-scatteredphoton suffers an energy loss and change in direction vector whereas acoherent or Rayleigh scattered photon only has its direction vectoraltered. In general x-ray radiography the source is a x-ray tube,although a radionuclide maybe substituted, used in a point, slit, slot,or area imaging configuration. The energy distribution and directionvector of the radiation from a x-ray tube are approximately known. Theseparameters are typically well-defined for a collimated radionuclidesource used in an application such as point-scan Compton scatter imagingand material analysis. A number of detection formats are in usedepending on the application. A planar detector geometry is typicallyutilized for applications such as mammography, angiography, and chestradiography which typically employ detectors such as x-ray film-screendevices, or storage phosphor screens, or image intensifiers coupled tocameras. Slit- and slot-scan formats are also available, usuallyincorporating improvements to the detectors and, in some instances, theradiation source. Additional image acquisition formats includering-shaped detectors or flat detectors for fan-beam or cone-beamtomography, respectively. Common detector geometries used in nuclearmedicine typically include one or more planar detectors, which arebasically standard Gamma cameras, with attached conventional collimatorsor ring detectors, used in Positron Emission Tomography. Imaging systemsbased on standard Gamma camera and related detector designs arefrequently used for a number of nuclear medicine studies such as heart,brain, thyroid, gastro-intestinal, whole body, and breast imaging,including scintimammography. A basic Gamma camera design employs alarge, planar array of scintillation crystals or a single, large, planarscintillation crystal optically coupled to an array of photomultipliertubes (PMTs). A conventional focused or unfocused collimator istypically mounted to the face of the Gamma camera. This inflexibleimaging system is then positioned such that the region of interestcontaining the source distribution is within the field of view. Itprovides a limited degree of spatial resolution and energy resolutionwhile removing some fraction of unscattered and scattered radiation thatwould otherwise degrade image quality. Unfortunately a substantialfraction of useful unscattered radiation is also attenuated. Anotherinfrequently used design replaces the conventional collimator with acoded aperture such as a uniformly redundant array aperture which isalso based on photon attenuation and is typically rigid. Commercialsystems may use one, two, or three Gamma camera detector units. Onecommercial system eliminates the use of scintillator crystals and PMTswith a rigid, planar, 2-D CdZnTe semiconductor detector manufactured byabutting four 2-D CdZnTe arrays of moderate size. Techniques forabutting 2-D silicon arrays are well-known in the art. Drawbacks toemploying large- or medium-sized 2-D CdZeTe arrays capable of highdetection efficiency include the difficulty of growing thick CdZnTecrystals with acceptable levels of defects and creating a low noise, 2-Darray readout structure on top of a large- or medium-size CdZnTecrystal. Grid collimators are still desirable for many applicationssince the direction vectors of detected photons are otherwise poorlydefined. A design which replaces a conventional collimator with arelatively thin, planar semiconductor, often Ge, array of moderate size,which serves as a Compton scatterer is referred to as a Comptonelectronic Gamma camera. This system is still being refined. Thedetector module array described below can be used in place of a standardGamma camera in a Compton Gamma camera system.

[0004] Nuclear medicine imaging applications are complicated by the factthat the spatial distribution of the source within a region of thepatient is poorly defined. One way to simplify this problem is to useemitted photons of known energies. For example, a source that has one ormore emission energies of a narrow energy bandwidth may be utilized. Theproblem now is the reconstruction of the source distribution rather thanthe calibration of the source distribution. The measured sourcedistribution, i.e., the apparent source distribution, represents thefiltered true source distribution, assuming self-attenuation is small.In certain nuclear medicine applications estimates of the true sourcedistribution are obtained by calibrating the contribution of the filter,which may be the patient, to the apparent source distribution. Photontransmission measurements are made in order to estimate the effect oftissue scattering and absorption or attenuation on radiation sourcemeasurements by using a reference source that is external to thepatient. Unfortunately, measuring photon transmission through the bodydoes not duplicate the actual imaging chain acquisition format used innuclear medicine where photon are transmitted out of the body. Photonsin the two instances do not traverse comparable paths.

SUMMARY OF THE INVENTION

[0005] In accordance with the present invention, a radiation detectionapparatus is provided for radiographic imaging and material compositionanalysis in which the apparatus can dynamically configure its arraygeometry and radiation detector parameters for a specific imaging taskor it can use an existing radiation detection geometry and settings.This invention is particularly suited for x-ray and gamma ray imaging innuclear medicine, including scintimammography, and x-ray radiography,specifically, x-ray mammography. There are several advantages inherentto this invention. Superior detectors in cost-effective formats can beutilized and detectors with different properties, including materials,resolution, response time and noise characteristics, can be used withinan array. One or more radiation detectors are incorporated into adetector module and one or more modules make up a detector module array.The detector modules transmit detected photon image data and relevantmodule parameters to a computer system which utilizes this informationto electronically-control the modules and in some cases attachedcollimators. This system is implemented using detector sub-arrays,comprised of one or more detector modules, and detector arrays in orderto enhance image quality or analysis capability. Conventionalattenuating or rigid geometry collimators, including ones characterizedby coded apertures, and unconventional, including x-ray optic,configurable (adaptive), and Compton scatter module, collimators can beemployed to improve the energy and/or spatial resolution for the photonradiation detection system. In a similar manner additional types ofradiation optic collimators such as neutron optic collimators orelectron optic collimators capable of focusing electric or magneticfields, can be used with neutrons or charged particles, respectively.

[0006] In a preferred embodiment semiconductor detectors withappropriate geometries, such as edge-on detectors; thick, linear arraydetectors; or small, thick, 2-D array detectors, are incorporated intodetector modules which are mounted within a frame and configured as anarray of detector modules. Detector modules contain one or moredetectors, possibly with different properties. A detector array containsone or more modules or types of modules. For nuclear medicine imagingapplications detector sub-arrays, comprised of one or more modules, orthe entire detector array can be positioned and oriented with respect tothe radiation source by an operator or by direct computer control.Collimators and shielding can be attached to or integrated into themodule, including interfacing with module electronics if appropriate.Modules communicate with the computer system which monitor and controlmodule and collimator parameters and collect and process radiation datarecorded by the detectors. Modules may communicate directly or through ashared network with the computer system. Computer-controlled servicesinclude sending electronic instructions to the module mounting hardware,the module, and the collimators, if appropriate. Electronic instructionscan initiate actions such as detector array motion, adjustment of therelative position or orientation of one module with respect to othermodules, manipulation of a collimator, and the modification of moduleoperating parameters, such as detector signal amplification, filtering,resolution, temperature, operating voltage or sampling rate. Sincepositioning machinery can be incorporated into the module, actuators canbe employed to adjust the position and orientation of the detector. Theactuators can also manipulate the positions and orientations ofappropriate collimators. A novel collimator design utilizes actuators toalter the configuration of a collimator. The computer-based monitor andcontrol capabilities can be used to track and adjust the locations ofmodules while they are in motion. Positions, orientations, and motion ofall detectors and relevant collimators are recorded and updated asneeded throughout the image acquisition process.

[0007] A typical nuclear medicine imaging session begins with anoperator selecting from a computer display menu a specific detectionsystem with pre-defined array geometry, collimator, and module settingsappropriate for the desired imaging task. The detector arrayconfiguration can already exist or it can be set up by the computersystem. Once a baseline detection system is established, an operator canthen adjust and fine tune the detector array position and settings orleave the detector array adjustments and tuning under computer control.While under computer control electronic instructions can be issueddynamically in response to detector module parameter values and detectedradiation data that is transferred to the computer system forprocessing, display, and storage during image acquisition or adaptiveimaging. Electronic commands can be used to control the array geometryand motion, detector module parameters, and some types of collimators.Thus an information feedback loop can be implemented as a means oftuning detection system parameters. For some imaging or analysisapplications it will be sufficient to configure the detector array basedon either a standard geometry, such as line, plane, open box, wedge,ring, cylinder, ellipse, ellipsoid, or sphere, or a contoured geometry,in order to compensate for the radionuclide distribution within thesubject and/or the shape of the subject at the region of interest. Forexample, configurations may be based on the breast size of a woman or onthe head size, waist size, or chest size of an adult, child, or infant.A versatile design allows at least a subset of these detector arraygeometries to be generated “on the fly”. A less-versatile design stillutilizes modules, but the modules are fixed within a specific detectorarray geometry or they are constrained to move to specific positions,for example, along a track, within a specific detector array geometry.Less-versatile designs reduce the mechanical complexity of the detectionsystem and may be sufficient for specific imaging tasks. An optionalcapability is to allow the entire array to undergo discrete or uniformmotion. The simplest example of this capability would be to scan aradiation source with a detector array comprised of a single detectormodule.

[0008] In another embodiment, semiconductor detectors are replaced byother types of suitable detectors, such as scintillation detectors, gasdetectors, liquid detectors, or superconducting detectors.

[0009] In another embodiment reference sources are introduced into thesubject and then imaged. The size, shape, intensity, and emissionspectrum of the reference sources are known. This allows measurements tobe made of photon attenuation due to material in the photon path priorto reaching the detector. This information can be used to estimate thetrue source distribution from measurements of the apparent sourcedistribution made during image acquisition in a nuclear medicine test.The reference source can also be used to focus the detector array inorder to tune the imaging chain.

[0010] In another embodiment detector modules and collimators areincorporated into x-ray radiography slit scan imaging systems. X-rayoptic collimators can be used to increase the intensity and modify thespectrum of the x-ray radiation that is recorded by the detector module.A single x-ray source is combined with a x-ray optic collimator and ax-ray detector module and used for a x-ray mammography slit scan system.Another improvement involves aggressively compressing sections of thebreast and acquiring separate images of the highly-compressed sectionsrather than acquiring a single image of the entire, mildly-compressedbreast.

[0011] The system of the present invention may utilize devices detailedin prior inventions for slit-scan or slot-scan radiographic x-rayimaging in which photons are detected directly using edge-on arraydetectors; small, 2-D semiconductor array detectors; or semiconductorarray detectors coupled to scintillators. This new device can also usethick, linear semiconductor array detectors and thick, small, 2-Dsemiconductor array detectors in addition to other types of detectors.Manufacturing costs for these detectors are much less than thoseassociated with large-area or moderate-area, thick, planar, 2-Dsemiconductor array detectors made from materials such as, but notlimited to, CdZnTe, CdTe, GaAs, Ge, Si, SiC, or HgI2. The detectorformat is also compatible with detectors such as thin, linearsemiconductor arrays or thin, small, 2-D semiconductor arrays coupled toscintillators. For example, thin, linear semiconductor arrays ofavalanche photodiodes coupled to scintillators can be used as radiationdetectors. This approach can be extended to include scintillatorscoupled to integrated photoemissive cathodes or small PMTs; small, gasmicrocapillary detector assemblies; or small superconducting arraydetectors. Consider a scenario in which radiation is incident upon aplanar edge-on detector. The detector thickness (height) now defines themaximum detector entrance aperture while the length or width of thedetector area now defines the maximum attenuation distance for edge-onradiation detector designs including semiconductor drift chamber,single-sided strip, and double-sided strip detectors, includingmicro-strip detector versions. Strip widths can be tapered or curved, inthe case of drift chamber detectors, if focusing is desired. In the caseof double-sided parallel strip detectors in which opposing strips areparallel, both electrons and holes can be collected to provide 2-Dposition information across the aperture. If strips on one side runperpendicular to those on the other side, then depth-of-interactioninformation can be obtained. If strips are segmented in either asingle-sided or double-sided parallel strip detector thendepth-of-interaction information can be obtained and readout rates canbe improved.

[0012] These and other advantages of the present invention will becomeapparent upon reference to the accompanying drawings and the followingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 illustrates a perspective view of a detector module array.

[0014]FIGS. 2a-2 c and 2 d(i)-(iii) illustrate perspective views ofvarious cylindrical, spherical and wearable detector array geometries.

[0015]FIG. 3a illustrates perspective views of box-shapedimplementations of detector arrays.

[0016]FIG. 3b illustrates an L-shaped detector array configuration.

[0017]FIG. 3c illustrates a compliant detector array configuration.

[0018]FIGS. 3d-3 f illustrate configurable arrays operated by actuatorarms.

[0019]FIGS. 4a-4 b illustrate perspective views of an edge-on detectormodule with an unconventional minifying/tapered capillary x-ray opticcollimator.

[0020]FIG. 5a(i)-(ii) illustrate a configurable dual x-ray refractivelens.

[0021]FIG. 5b(i)-(ii) illustrate nested refractive lenses.

[0022]FIG. 6 illustrates a perspective view of an electronicallycontrolled configurable collimator.

[0023]FIG. 7a illustrates an electronically controlled configurablerefractive lens with an associated configurable x-ray mirror andradiation source.

[0024]FIG. 7b illustrates a fixed-focal length capillary x-ray lens withan associated configurable x-ray mirror and radiation source.

[0025]FIGS. 7c-7 d illustrate an array of capillary x-ray optic lensesaligned with an array of radiation sources in the form of a cylindricalanode.

[0026]FIG. 7e illustrates a wedge-shaped capillary x-ray optic lensaligned with a dense array of radiation sources.

[0027]FIG. 8 illustrates a planar detector array comprised of stripdetector modules positioned within a frame.

[0028]FIG. 9a illustrates a capillary x-ray lens system designed with asingle gantry arm.

[0029]FIG. 9b illustrates a multiple gantry arm system.

[0030]FIG. 9c illustrates a system utilizing additional x-ray opticsintroduced between a capillary x-ray lens and compression plates.

[0031]FIGS. 10a-10 b illustrate a system incorporating flat andcontoured compression plates.

[0032]FIG. 10c illustrates the use of overlapping images to ensurecomplete imaging of the breast.

DETAILED DESCRIPTION

[0033] General Detector Array

[0034] In one embodiment of the present invention, as illustrated inFIG. 1, a detector array 1000 preferably incorporates separate, discretedetector modules 102, illustrated here as edge-on or strip/micro-stripdetectors, configured in a planar geometry to optimize the detection ofincident radiation 107. The detector array 1000 may be utilized as partof a gamma camera. Currently, gamma cameras are not based on detectorarrays such as detector array 1000 which incorporates discrete modules102.

[0035] Detector modules 102 utilize one or more detectors 101, typicallyarray detectors, which can have different properties. Note that severalof the modules 102 include more than one detector. Additionally, lineararray or small, 2-D array semiconductor detectors may be incorporatedinto the detector modules 102. Each module 102 also includes a base 106and a communications link 103.

[0036] The base 106 preferably contains detector electronics, powermanagement components, temperature control components, and a data orinformation channel for communicating with the computer system. The base106 may also incorporate a module electronic readout unit that includesa signal conditioner or filter, an amplifier, an analog-to-digitalconverter, and a communication interface. Additionally, the detectormodule 102 may be coupled to an electronically-controlled thermoelectriccooler or other temperature regulating device which resides in thedetector module base 106. In this embodiment, the temperature-regulatingdevice provides temperature control for the detector module 102 and itselectronic readout unit.

[0037] The communications link 103 provides power to the module 102 andconnects the base 106 to a computer system. Through the attachment withthe base 106, the link 103 enables a computer system to control theconfiguration of the module 102. The communication link 103 preferablyis used to off-load the digitized detector radiation data to a computersystem for analysis and image reconstruction. The computer system, whichcan include general purpose, dedicated, and embedded computers, providesmonitor and control services to modules 102 and to the entire detectorarray 1000. The computer system evaluates module, detector arrayparameters, and the detected radiation image data. The detected data isprocessed and can be displayed and stored if desired. Additionalrelevant module information, such as temperature, amplifier settings,detector voltages, position, orientation, and motion information, can betransmitted to this computer system over the communication link 103.Alternatively, a separate communication channel may be incorporated totransfer the additional information between the module 102 and thecomputer. The computer system transmits instructions that update thedetector array 1000. This establishes a dynamic information feedbackloop that is useful for adaptive imaging.

[0038] Each module 102 may optionally have its own radiation shielding104 and collimator 105 mounted on the wall of the module 102, althoughonly one module is shown with these items for clarity. Module walls aretypically thin, which permits radiation-shielding 104 to be attached tothe module wall or inserted between adjacent modules 102 when needed. Asillustrated in FIG. 1, collimators 105 are placed in operable contactwith the detector modules 102. However, the array 1000 is capable ofoperating without collimators 105. Even in the absence of collimators105, collimation exists to a limited extent because the modules 102 arediscrete and physically separated. In this alternative embodiment, thearray 1000 is designed to detect incident radiation 107 using detectormodules 102 without attached collimators 105.

[0039] Turning back to the embodiment illustrated in FIG. 1, bothconventional and unconventional collimators 105 can be attached to thedetector module 102. If the collimators 105 are capable of beingelectronically-controlled to perform mechanical alignment or tomanipulate unconventional collimators, then the module 102 may utilizethe communications link 103 to provide power management andcommunication capability to the collimator 105. The communication link103 is also used to transmit collimator parameters and settings betweenthe module 102 and the computer system.

[0040] A detector array 1000 can be comprised of more than one type ofdetector module 102. A number of array geometries, in addition to thestandard planar detector array format, can be utilized. This design mayalso be implemented by using semiconductor detectors coupled toscintillators as well as other types of detectors. These detectors aredescribed in Nelson, U.S. Pat. No. 4,560,882, which is incorporated byreference for all it discloses and describes. Limiting the focusing ofthe modules 102 using edge-on strip detectors is possible by taperingthe edge-on strips, as described in Nelson, U.S. Pat. No. 4,937,453,filed May 6, 1987, which is hereby incorporated by reference for all itdiscloses and describes.

[0041] The increased detector density is useful for enhancing theimaging of select regions of the subject. For example, the array 1000illustrated in FIG. 1 is particularly suited to form large area, 2-Ddetector arrays, such as those described by Nelson, U.S. Pat. No.4,937,453, due to the close proximity of multiple modules 102.

[0042] The detector array 1000 and individual detector modules 102 canbe scanned or dithered, i.e. moved repeatedly between adjacentlocations, as needed so as to provide appropriate sampling of spatialregions which would otherwise be ‘dead areas’ due to a lack of detectorsat those positions. Scanning motion is suitable for sampling regionsthat would otherwise require multiple detector modules to fill.Dithering is suitable for sampling regions that are typically less thanthe size of detector pixels. A detector module 102 can incorporate morethan one detector 101 with the same or different properties. A detectorarray 1000 can use more than one type of detector module 102. Forexample, detectors 101 or detector modules 102 with different energyresolutions, spatial resolutions, stopping powers, and readout rates canbe combined in order to match the imaging characteristics of the deviceto specific as well as general applications. Temperature management,typically cooling, of the detectors 101 may be utilized as needed.Preferably the detectors 101 will operate at or near room temperaturefor applications in nuclear medicine, but this may not always bepossible. Several safety features can be included with the detectorarray 1000 to restrict its speed of motion and proximity to the subject.These can include optical and acoustic range sensors as well aspressure-sensing devices. Computer-controlled positioning and sensordevices have been widely used for many years in applications such asmedical imaging, robotics, factory automation, precision machine tools,micromachines, and aviation.

[0043] An external container (not shown) preferably is typicallyemployed to shield the detector array 1000 and any electronic componentsfrom external electromagnetic fields and physical contact.

[0044] Specialized Detector Arrays

[0045] The present invention includes specialized detector arrays suchas those illustrated in FIGS. 2a-2 d. FIGS. 2a-2 d illustrateperspective views of fixed cylindrical-like (FIG. 2a), spherical-like(FIG. 2b), and wearable (FIG. 2c) detector array geometries.

[0046] Cylindrical and Spherical Detector Arrays

[0047] In FIGS. 2a and 2 b, edge-on detector modules, 102(a) and 102(b),are capable of motion along tracks, 110(a) and 110(b). Such acharacteristic enables the modules 102(a) and 102(b) to sample gapsbetween individual modules. Turning to FIG. 2a, the modules 102(a) areshown with side shielding 112 and a radiation source 111. The shielding112 may be included on the modules 102(a) in order to minimize thedetection of radiation escaping from neighboring detectors. The modules102(a) are configured to move in a cylindrical fashion along the tracks110(a).

[0048] Turning to FIG. 2b, the tracks 110(b) are configured to allow themodules 102(b) to move in a spherical motion with both up and down andside to side directionality possible. In both FIG. 2a and FIG. 2b, themodules, 102(a) and 102(b), move independently along tracks, 110(a) and110(b), as part of a detector array or detector sub-array, or both typesof motion can be executed in order to improve the sampling uniformity ofthe subject. The optional use of a flexible track (not shown) permitsthe detector modules, 102(a) and 102(b), to follow the contours of thesubject more closely by enabling the modules, 102(a) and 102(b), to movein conformity with the subject. Using a flexible track would allow for acontoured geometry.

[0049] The computer system keeps a chronological, real time record ofmodule and array parameters, including position and orientation ofdetectors and collimators, motion, detector amplification and noise,during image acquisition and during detector array calibration.

[0050] Detector array configurations such as those shown in FIG. 2a andFIG. 2b may be extended or filled-out to form a more complete cylinder,such as a ring shape, or even spherical arrays of detectors. Detectorarray configurations may also be shaped to fit other standardgeometries, including slit, slot, line, plane, open box, wedge, ellipse,ellipsoid, or a combination of geometries. Collimators can be employedwith individual edge-on detectors, such as illustrated in FIG. 1.

[0051] Wearable Detector Arrays

[0052] Turning now to FIG. 2c, a wearable detector array 2000(a) in theform of a detector vest, similar in form to an upper torso “body armor”shell, a down-filled winter vest, or a breastplate, is illustrated. Thedetector vest 2000(a) is designed such that it approximately conforms tothe shape of the patient. Straps 123 may be included to allow thepatient to securely wear the detector vest 2000(a). Straps 123 may alsobe used with other wearable detector arrays. For example, a wearablehelmet could incorporate an adjustable chinstrap. The adjustable straps123 also permit the detector vest 2000(a) to be positioned at thedesired location for a range of body types.

[0053] A detector array 1000, sufficient in size for imaging the heart,is incorporated into the detector vest 2000(a). This configuration canbe cost-effective for particular cardiac imaging studies since the areaof the detector array, and any attached collimators, is not much largerthan the projected area of the heart onto the plane of the detectorarray. An additional benefit is the reduction in weight that is possibleby employing a small detector array and collimator. A detector vest2000(a) such as that illustrated in FIG. 2c enables effective samplingof the region of interest throughout the examination, mitigatingproblems due to undesired patient motion. Wearable detector devices mayalso permit claustrophobic patients to undergo testing since one ormultiple large gamma camera heads will not be positioned about thepatient so as to create a confining effect. Communication links 103 areused to facilitate communication between the detector array 1000 and acomputer and to supply power to the detector modules 102.

[0054] An optional support harness 122 reduces the additional stressimposed upon the patient that may be generated due to the weight andbulk of the detector vest 2000(a). If the detector vest 2000(a) is tooheavy or bulky for the patient then a flexible suspension system usingthe support harness 122 is employed to provide at least partial supportfor the detector vest 2000(a). The use of a support harness 122 is verysimilar to the concept of using a training harness for a patient oranimal recovering from injuries or for simulating effects such asreduced gravity for an astronaut. A flexible suspension system can alsobe employed with other wearable detector devices if needed.

[0055] An alternate implementation of a wearable detector which stillpermits limited mobility is a detector array configuration that issupported by a stand with adjustments for height, tilt, and rotation.The patient presses the appropriate body part (head, neck, chest,stomach, etc.) against the detector array configuration while stationaryor performing an exercise regimen. This imaging format maintains areasonable alignment between the detector array and body region and issimilar in principle to using exercise equipment such as cross-countryski trainers where an individual presses the hips or stomach against anadjustable pad.

[0056] Detector arrays can be incorporated into similar equipment tocreate wearable detector arrays such as wearable detector helmets/headgear, detector neck braces, detector brassieres, and detector belts orgirdles. FIG. 2d(i)-2 d(iii) illustrate different wearable devices,namely a detector vest (2000(b), FIG. 2d(i)), a detector helmet(2000(c), FIG. 2d(ii)), and a detector brassiere (2000(d), FIG.2d(iii)), that use open frames, 124(b)-124(d), in the shape of thedesired geometry for mounting detector modules and collimators. The openframes 124(b)-124(d) provide a grid for mounting the detector array 1000and any associated collimators to examine different sections of thesubject. For example, a detector array 1000 could be mounted on an openframe detector vest 2000(b) so as to image the heart and lungs andanother detector array 1000, possibly with modules 102 of differentproperties and collimators 105, could be mounted so as to image thekidneys and gall bladder. The many possible configurations of detectorarrays 1000 that can be implemented in a wearable device such as awearable detector vest enable it to provide the same types of views,including 180 degrees, 240 degrees, and 360 degrees, which single andmultiple head Gamma cameras are able to acquire.

[0057] Additionally, compressible pieces of foam or other expandablebladders 125 may also be attached inside a wearable detector in order toallow for a further customized fit to the patient. Bladders 125 are alsoutilized to minimize contact between the patient's body and rigid areasof the wearable detector, including the detector array 1000 withdetector modules 102 and collimators 105. The bladders 125 are directlycomparable to the use of foam and expandable bladders in athletic gearsuch as football helmets. If the pressure exerted by an expandablebladder 125 is modulated, an established technique that is used toassist circulation in the legs of bed-ridden patients, then specificphysiological studies that depend on circulation, including breastphysiology, can also be conducted.

[0058] If needed, the patient can be cooled by circulating air or acontained liquid between regions of the wearable detector and thepatient's body that do not interfere with image acquisition. The powerand communication connections, such as the communications links 103,that interact with the detector arrays 1000 can also interact with orcontrol cooling devices (not shown) and expandable bladders 125.

[0059] Detector arrays 1000 are capable of being installed in fixedconfigurations in wearable detectors or they can be designed to beremovable. For example, removable detector arrays 1000 may be configuredto snap into pre-defined positions, dynamically establishing power andcommunication connections with the power source and computer,respectively, and permitting customization. The locations of thedetector arrays 1000, and modules 102 within the array 1000, on thewearable device are transmitted to a computer that communicates witheach detector module 102, as in the case of the other detector arraygeometries already discussed. Wearable detectors may be of particularvalue in situations where involuntary or required patient motiondegrades image quality. For example, a patient could wear a detectorvest 2000(a) or an open frame detector vest 2000(b) while undergoing atreadmill cardiac stress test. Instead of the patient trying to maintainthe same position with respect to the detector vest, 2000(a) or 2000(b),the detector vest 2000(a) or 2000(b) remains aligned with the patient. Apatient can also wear the detector vest 2000(a) or 2000(b) while lyingdown or riding a stationary bike. The ability to utilize detector arraysin situations where involuntary or required patient motion may occuralso applies to wearable detectors other than detector vests (2000(a) or2000(b)), including helmets 2000(c), neck braces or neck wraps (notshown), brassieres 2000(d), and belts/girdles (not shown).

[0060] A wearable detector may allow multiple studies, using multipleradionuclide tracers and appropriate detector energy windows, to beconducted at one time. For example, thallium, technetium 99 m, and apositron emitter used together could permit metabolism, regional bloodflow, perfusion abnormalities, and ventricular function to be studiedwhile exercising.

[0061] Configurable Detector Arrays

[0062] Turning to FIGS. 3a-3 d, movable detector arrays are illustrated.When a detection system involves movable detector arrays 1000(a), themotion of the detector arrays 1000(a), or the detector modules 102, donot have to be confined to a track. Another implementation of thedetection system permits the detector array 1000(a) to move as a unit,but the modules 102 within the array can still be positionedindependently. This allows the array 1000(a) of detector modules 102 tobe refocused or individual detector modules 102, as well as theradiation detectors 101 incorporated into those modules 102, to berepositioned as required in order to optimize detection for a specifictype and distribution of radionuclide. For example, a detector array1000(a) of fixed or limited configurability can be used in a plane, “L”(FIG. 3b), or open box (FIG. 3a) geometry. FIG. 3a shows perspectiveviews of “box”-shaped implementations of detector arrays 1000(a) forimaging the heart. Simple versions include standard geometries that aresomewhat fixed. In this example, variants of a rectangular shape arepossible. Detector arrays 1000(a) are present on two/“L”-shaped (FIG.3b), three (not shown), or four (FIG. 3a) sides of the subject. Eachdetector array 1000(a) is positioned by an electronically controlledactuator arm 130.

[0063] Turning to FIG. 3c, a compliant detector array 1000(b) is shown.The compliant detector array 1000(b) is comprised of detector modules102 that are small in size, offering more orientation and positioningoptions. The compliant detector array 1000(b) enables the array 1000(b)to follow the approximate contour of the region of interest, as shown inFIG. 3c, thereby allowing for a contoured geometry for the array1000(b). Positioning may also be accomplished with or without the aid ofactuator arms 30. As illustrated in FIG. 3c, the flat side of thesubject may be positioned immediately next to a conventional, planardetector array 1000 so that the system does not require an actuator arm.

[0064] A gantry that would normally be used for encircling the subjectis not necessary in this embodiment since the flat side of the subjectcan be positioned next to the planar detector array 1000. The computersystem monitors and records in real time the position and orientation ofthe detector arrays 1000 and 1000(b), including detectors modules 102,detectors 101, and collimators 105, and relevant motions with respect tothe subject.

[0065]FIG. 3d illustrates a configurable detector system 3000 thatutilizes configurable arrays 1000(a) manipulated by computer-controlledactuator arms 130. The actuator arms 130 are able to move along slidesor rails 131 within a gantry 135, thereby allowing the detector system3000 to be reconfigured “on the fly”. The actuator arms 130(a) are moreflexible than the actuator arms 130 shown in FIGS. 3a and 3 b due to theinclusion of rotation capability. The lower detector module array 133 isshown as stationary since the subject is positioned next to it in thisconfiguration. Actuator control of the lower detector module array 133may be implemented if desired, thereby allowing dynamic position of thelower detector array 133 in the same manner as the other detector arrays1000(a) illustrated. Position and orientation information of any of thedetector arrays 1000(a), 133 with respect to the subject is recorded.

[0066]FIG. 3e illustrates one example of configurable arrays 1000(a)mounted on actuator arms 130(a) that are capable of rotational motionand additionally capable of tilting the arrays 1000(a). The ability totilt the arrays 1000(a) with respect to the actuator arms 130(a) makesthe arrays 1000(a) adaptable to a greater range of patient geometries.The overlap between detector arrays 1000(a) is reduced providing eacharray 1000(a) with its own actuator arm 130(a), thereby enabling themovement of each array 1000(a) independently of the other arrays1000(a). The actuator arms 130(a) preferably are capable ofbidirectional movement along a gantry 135. Communications links 103enables a computer system to control the actuator arms and thepositioning of the arrays 1000(a).

[0067] Alternatively, as illustrated in FIG. 3f, three detector arrays1000(1)-(3) may be joined in operable connection with each other withonly one of the arrays 1000(2) attached to the actuator arm 130(b). Thearrays 1000(1)-(3) are connected such that a middle array 1000(2) isconnected on each end of the array 1000(2) to one end of the otherarrays 1000(1), 1000(3). The arrays 1000(1)-(3) are connected by hinges137 that enable arrays 1000(1) and 1000(3) to be tilted relative toarray 1000(2). The hinges 137 preferably are configured such that thearrays 1000(1) and 1000(3) are able to move in a bilateral directionaway from and towards the middle array 1000(2) while also being able totilt relative to the middle array 1000(2). The middle array 1000(2) isadditionally in operable connection with the distal end of the actuatorarm 130(b). As with the embodiment illustrated in FIG. 3e, the actuatorarm 130(b) is preferably capable of bidirectional movement along agantry 135. A communications link 103 is provided that enables acomputer system to control the movement of the actuator arm 130(b) andthe arrays 1000(1), 1000(2), and 1000(3). Additionally, arrays 1000(1)and 1000(3) are able to be positioned manually rather than solely bycomputer remote control.

[0068] Unconventional Collimators

[0069] Turning to FIG. 4a, a perspective, frontal view of an edge-ondetector module 102 with an unconventional minifying or taperedcapillary x-ray optic collimator 140 is shown. This collimator 140 hasincreased the apparent aperture of the detector module 102, therebyenabling the detector module 102 to detect a larger proportion of thesource radiation. Additionally, the detection of scattered ornon-directional photons are decreased. The collimator 140 output face,or aperture, is closely matched to the actual detector aperture. Thisconfiguration allows for the design of the module 102 to remain compact.FIG. 4b shows a side view of the same detector module 102 with aminifying capillary x-ray optic collimator 140. Additionally, anoptional configurable x-ray optic collimator 141, which is aconfigurable multilayer x-ray mirror that functions as a narrowbandwidth and directional filter, is introduced.

[0070] Conventional, including coded apertures, collimators andunconventional collimators can be used with the present invention.Typical conventional attenuating, rigid geometry collimating devicesrange from simple pinholes and slats or septa to focused and unfocusedgrids. Unconventional collimating devices include x-ray optics,configurable collimators, and Compton scatter module collimators. Costand imaging requirements, including types of detectors, spatialresolution, radiation energies, size of subject, and source distributionand intensity, will influence the selection of collimators. Examples ofx-ray optics include devices such as x-ray mirrors, Bragg crystals,pyrolitic graphite crystals such as those described in Nelson et al.,U.S. Pat. No. 4,958,363, filed Aug. 12, 1988, and Nelson et al., U.S.Pat. No. 4,969,175, filed May 10, 1989, which are hereby incorporated byreference for all they disclose and describe, capillary x-ray optics,refractive x-ray lenses, diffractive x-ray lenses and structures, andx-ray Fresnel lenses. If the x-ray optic device or collimator has theability to focus radiation then it may be used to expand the apparentaperture of the detector, as shown in the module 102 illustrated in FIG.4a, thereby making more efficient use of the radiation source. Minifyingcapillary x-ray lenses, refractive x-ray lenses, diffractive x-raylenses and structures, curved x-ray mirrors, and x-ray zone plates areexamples of focusing x-ray optic devices. For typical nuclear medicineapplications the x-ray optic collimator may be integrated with thedetector module 102, as in FIG. 4a, or held in a separate frame and thenaligned with a detector module 102, as in FIG. 5b(ii).

[0071] An alternative design is to use the dual lens or nested lensconfigurations of FIG. 5a(i), FIG. 5a(ii), FIG. 5b(i), and FIG. 5b(ii)to produce multiple focused beams, but each beam is directed to acorresponding detector module. In this instance multiple slit-like beamsare shown. A similar design has been described previously, but narrowbandwidth x-ray mirrors were described rather than refractive lenses.Nelson et al., U.S. Pat. No. 4,958,363, describes such a design. Thepracticality of utilizing specific x-ray optic devices is influenced byseveral factors including: the size and distribution of the radiationsource, the energy spectrum of the radiation, physical size limitationsof the detectors used in the detector array, the imaging format, whichmay be an internal radionuclide source or an external radiation source,and space requirements, and the cost and maintenance of the x-ray opticdevices. If the narrow bandwidth filtering directional discriminationproperties of a x-ray mirror are not needed or the operational energyrange is better suited to refractive or capillary x-ray optics thenthese devices may be preferred.

[0072] Turning to FIG. 5a(i) and FIG. 5a(ii), perspective views ofconfigurable dual x-ray refractive lenses 150 that incorporaterefractive slats 153 are shown. This design is similar in principle to adual mirror x-ray telescope. The lens includes a support 152 for therefractive slats 153. This lens increases the apparent aperture of aslit-like or slot-like detector. The focal length of the lens needs tobe accounted for when determining where to locate the lens relative tothe source and detector.

[0073] As illustrated in FIG. 5b(i) and FIG. 5b(ii), this configurationmay be modified and extended by nesting pairs of x-ray refractive lenses150. The nested pairs of configurable or fixed refractive lenses 150 maybe mounted in an assembly 151 similar to the nested x-ray mirrortelescopes that have been used in x-ray astronomy for a number of years.Practical nested lens will require refractive lenses with thin shellsused as supporting structures. The efficiency of the nesting techniquewill improve if the refractive lenses 150 can be densely packed.Therefore, a relatively thin support structure 151 is preferred.

[0074]FIG. 6 shows a perspective view of an electronically-controlledconfigurable collimator 160 which uses electronically-controlledconfigurable elements, in this case two sets of configurable slats 161or septa made from appropriate photon attenuating materials such as tin,lead, tungsten, or uranium. The two sets of adjustable slats 161 includea longer length slat set 163 and a set of shorter length slats 164. Thecollimator 160 includes hinges 162, 167 and a support frame 165 thatfacilitates the manipulation of the slats 161. The configurablecollimator 160 can be implemented so that the slats 161 moveindependently or in synchrony, similar to the operation of windowblinds. The long slats 163 running the length of the detector mayreplaced with slats that are subdivided such that each subdivided slatis individually manipulated for each corresponding detector element. Theshorter slats 164 are configured so that a set of two shorter slats 164defines the edges of a detector module 102, with one short slat 164defining a distal edge and the other short slat 165 defining a proximaledge of the detector module 102. The slats 163, 164 may be manipulatedthrough the use of devices such as actuators, miniature motors, andpulley mechanisms. Moreover, the collimator 160 is capable of beingcontrolled remotely through its communications link 103. Collimator 160may be utilized with the detector modules 102 of any of the detectorarrays 1000 disclosed herein.

[0075] Configurable collimators may utilize actuators, includingelectromechanical biopolymers or piezo-drivers, small motors,micromachines, or screw drives, to control parameters such as aperturesize and orientation. In alternative embodiments of the configurablecollimator, refractive, diffractive, or reflective elements aresubstituted for the attenuating elements, thereby forming configurablex-ray optics. An immediate extension of this approach is to abutconfigurable collimators to create 2-D arrays of attenuating,reflective, diffractive, or refractive slats. For example, if reflectiveslats are made sufficiently small these elements will assume the role ofmicromirrors, resulting in highly-configurable micromirror array x-rayoptics which can be electronically-controlled. Optical micromirrors arecommercially available. Additional functionality can be added if eachmicromirror is constructed on an actuator or a deformable surfacecontrolled by actuators. By manipulating the elevation as well as thetilt of the micromirrors, adaptive 3-D x-ray optics can be formed.

[0076] A variation of this device is to replace the x-ray mirrorcoatings with diffractive or refractive structures. In a similar manner,neutron mirror coatings or refractive or diffractive structures can beused with micromirrors for neutron radiography applications.

[0077] Configurable x-ray optics are useful not only for modifying theradiation incident on the radiation detector but also for modifying theradiation emitted by a radiation source, including a radionuclide orradiographic x-ray source. For example, the configurable dual x-rayrefractive lenses 150 shown in FIG. 5a(i) and FIG. 5a(ii) useelectro-active, electromechanical biopolymer actuators to adjust therefractive elements in the lenses.

[0078] Turning to FIG. 7a, a perspective view of an electronicallycontrolled configurable refractive lens 150 and a configurable, singleelement x-ray mirror 141 are illustrated. The apparatus in FIG. 7aprovides an example of compound x-ray optics. The refractive slats 153incorporate an electromechanical biopolymer material that functions asan electronically controlled actuator, thereby facilitating themanipulation of the refractive slats 153 without requiring a separateactuating mechanism. The tilt of each element can beelectronically-controlled by manipulating the electro-active biopolymermaterial directly.

[0079] In FIG. 7b, the configurable refractive lens 150 is replaced witha fixed-focal length capillary x-ray lens 70, which is paired with theconfigurable, single element x-ray mirror 141. The x-ray mirror 141provides spectral and directional filtering and is less expensive tomanufacture than a focused x-ray mirror. If additional focusing isdesired a focused x-ray mirror or a refractive x-ray lens could be usedin place of the single element x-ray mirror 41. If additional spectralor directional filtering is not needed, then the flat x-ray mirror 141can be eliminated.

[0080] The simple configurable collimator implementations describeherein preferably use electronically-controlled mechanical means to tiltrigid elements or flex elements into the desired position according topredetermined settings or based on detector feedback. More complicatedimplementations preferably use actuators or micromachines to adjust thesurfaces of reflective or refractive elements. The technique of usingdetector feedback to control actuators is well-known in the field ofadaptive optics where non-ionizing electromagnetic radiation istypically employed.

[0081] Turning now to FIG. 7e, another collimator encompassed by thepresent invention is illustrated. A wedge-shaped capillary x-ray opticlens 180 is aligned with a very dense array of radiation sources 181.The dense array of radiation sources 181 effectively forms a continuoussource of radiation since the sources are packed in extremely closeproximity to each other. This configuration allows the generation of aslit-like beam 182 from the radiation source 181. Here, the capillaryx-ray lens 180 can be simplified for a slit scan application sincefocusing is only needed along one dimension. The wedge-shaped capillarylens 180 offers focusing along one direction, such as along the width ofthe slit. If adequate intensity can be obtained without focusing then anon-focusing capillary lens may be substituted into this configurationto function simply as a highly directional collimator. With thisembodiment, a rotating cylindrical anode tube could also be used withthe extended focal spot or the extended focal spot could be simulatedusing a fast scanning electron beam. Alternatively, other x-ray opticdevices may be substituted for, or used in conjunction with, thecapillary x-ray lens 180. This technique requires the use of x-rayoptics of increased complexity further from the center of the focal spotdue to the increasing angle of incident radiation at the x-ray optics,assuming the goal is to generate approximately parallel x-rays. Analternative to parallel scanning slits is to use slits in a radialgeometry, permitting rotational scanning. This scanning format could beused in mammography with either flat or curved compression plates.

[0082] Another technique for reducing the scan time is to increase thenumber of scanning slits. The X-ray optics described in FIG. 5b(ii)could be employed for this purpose. As seen in FIG. 5b(ii), all slitsand their detectors can share a single focal spot.

[0083] Alternatively, each slit can be aligned with its own focal spot.For example, a slit scanning system for mammography could use at leasttwo x-ray tubes, i.e., two focal spots, each with a focusing x-ray opticcollimator 70 and an aligned detector array 1000 on the other side ofthe subject, as seen in FIG. 9b.

[0084]FIG. 8 illustrates a novel, unconventional collimator 190 thatextends the principle of a detector array based on modules to asemiconductor Compton scatter detector array based on modules. This newcollimator 190 preferably is used for nuclear medicine Compton scatterimaging. The new collimator 190 is also capable of being used with astandard Gamma camera or an array of detector modules to enhance thecurrent Compton electronic Gamma camera design. FIG. 8 shows aperspective view of the Compton scatter module collimator 190 whichpreferably is a planar detector array comprised of strip detectormodules 191, which are double-sided, crossed strips for 2-D resolution,positioned within a frame. In this implementation, modules 191 whichincorporate relatively thin, linear or 2-D semiconductor detectors canbe configured into a number of geometries compatible with the standardGamma camera or array of detector modules. Relatively thin, linear or2-D semiconductor detectors will be much less costly to manufacture thanthe thick, moderately large, 2-D semiconductor array detectors currentlybeing tested and are therefore preferred.

[0085] The strip detector modules 191 shown in FIG. 8 are double-sided.The back-side strips (not shown) are oriented at 190 degrees to thefront-side strips, thereby providing 2-D information. Compton scatterphoton radiation is formed from this configuration and the radiation isdetected by a Gamma camera. The Gamma camera preferably is locatedbehind the collimator 190 and is not shown in FIG. 8. A connection 192preferably is provided to transmit output from each detector module 191to signal processing electronics. Module parameters, such as, e.g.,temperature, electronic readout, and power are electronically controlledvia the connection 192. In one embodiment, the modules 191 are alsocapable of interfacing with other modules 191 in order to shareresources such as power, cooling, and communications. Fixed orconfigurable collimator geometries of greater complexity can beimplemented as needed. A supporting frame 193 preferably is provided inorder to maintain the positioning of the detector modules 191.

[0086] In one embodiment, the detectors modules 191 are immersed in alow temperature coolant in order to prevent operating temperatures thatare too high. In this embodiment, all of the modules 191 can beencapsulated together in a container that holds the coolant. Thecollimator 190 can also be dithered to compensate for dead spacesbetween detectors that are closely spaced.

[0087] Imaging Systems

[0088] The present invention may also be employed in x-ray radiographicimaging systems. Operational energy ranges and spatial resolutionrequirements will be different in many instances from those that areused in nuclear medicine. Two additional factors that impact the designof nuclear medicine and x-ray radiography imaging systems are the imageacquisition time and the properties of the radiation source. Aconsequence of the short acquisition times required in x-rayradiography, which are fractions of a second to multiple seconds for 3-Dimaging, is the need for an intense radiation source or a subject who isnot heavily attenuating. Some nuclear medicine study scan times canexceed 15 minutes. Typically both nuclear and x-ray radiographic imagingmodalities benefit from an increase in the apparent intensity activityof the source. Benefits include reduced acquisition times and/orimproved statistics. The source distribution and location are poorlydefined in many nuclear medicine imaging applications, limiting thevalue of customized focused photon optics for directing more of thesource radiation to a detector. In contrast to this situation, thesource distribution, which is highly localized, and position are usuallywell-defined in x-ray radiography. Focusing x-ray optic collimators canbe designed for a specific x-ray tube focal spot distribution. Thiswould not be practical given cost constraints for most nuclear medicineimaging applications. X-ray radiography applications that could use oneor more detector modules include slit, slot, or CT scanning.

[0089] X-ray mammography is a radiographic imaging application that usesrelatively low x-ray energies, increasing the number of viable detectorand unconventional collimator choices. For example, the source shown inFIG. 7b can be the focal spot of a x-ray tube. The tube is preferably asource with a well-defined location and reasonably well-defineddirectional and spectral properties. The focused capillary x-ray lens70, or a refractive lens, a diffractive lens, a curved or configurablex-ray mirror, nested lens, or combinations of x-ray optic collimators,would be used to increase the intensity of radiation that wouldultimately be detected by a slit-shaped detector, such as an edge-ondetector, after passing through the subject. This configuration isillustrated in FIG. 9a.

[0090] Gantry Imaging Systems

[0091] Turning to FIG. 9a, a perspective view of a rotatable gantry unit1200 with an adjustable arm 1100 configured to hold an x-ray tube 1102,incorporating a radiation source 111 and a capillary x-ray lens 70, anda detector array 1000 is shown. The array 1000 may use either analog ordigital detector modules. The gantry system 1200 rotates about an axisand has an arm 1100 that allows for further adjustment in abidirectional manner. As shown, the gantry system 1200 is adapted forx-ray mammography applications by incorporating a pair of compressionplates 1101 that are used to position a subject breast. This design iscomparable to a traditional x-ray film-screen mammography-imaging unitwhich utilizes a rotatable gantry. The x-ray tube 1102 is aligned withthe detector array 1000. The x-ray tube 1102 and detector array 1000 arethen scanned as a unit.

[0092] As seen in FIG. 9c, if additional spectral and directionalfiltering of the radiation beam is desired then a configurable x-raymirror 1110 can be inserted between the capillary x-ray lens 70 and thecompression plates 1101 holding the subject compressed breast 1111, asseen in FIG. 9c. A second x-ray mirror or crystal may be positionedbetween the compression plates 1101 and the detector array 1000 if evenmore spectral and directional filtering is desired. In some instances arefractive x-ray lens can be used in place of the x-ray mirror 1110,providing focusing and some filtering instead of the spectral anddirectional filtering provided by a configurable x-ray mirror.Collimators 1112 are provided on either side of the compression plates1101 in order to limit the x-ray beams that are passed through thesubject breast 1111. The collimators 1112 concentrate a segment of thex-ray source output into a slit or slot geometry.

[0093] Turning now to FIG. 9b, a dual gantry system 1300 that combinestwo individual gantry arms 1110 is illustrated. The separation distancebetween the gantry arms 1110 can be adjusted for scanning objects, forexample, compressed breasts, of various sizes. As with the gantry system1200 shown in FIG. 9a, the dual gantry system 1300 may also be rotatedand the arms 1110 are adjustable in a bidirectional manner. Compressionplates 1101 that are typically employed in mammography imaging may beincorporated into the dual gantry system 1300 but are not shown in FIG.9b. An x-ray tube 1102, incorporating a radiation source 111 and acapillary x-ray lens 70, and a detector array 1000 are attached to eacharm 1110 and are adjustable by virtue of being mounted on the arms 1100.Each unit would only be required to scan half as far as a single unitsystem, reducing the total scan time and x-ray tube operational time by50%.

[0094] Many gantry designs are possible, including portable gantriesdesigns, which are in use with portable x-ray and Gamma camera imagingsystems. These gantry designs allow improved detector positioning withrespect to the heart in comparison to standard Gamma camera designs.

[0095] Composite Anodes

[0096] The present invention is additionally directed to the generationof focused radiation by operating a composite anode operating inconjunction with x-ray optic lenses. Turning to FIG. 7c, a compositeanode 73 comprised of N types of disks is illustrated. In this case Nequals 2 and the disks preferably are molybdenum and rhodium, although Nequals 1 or N greater than 2 can be constructed. For example, the disksare capable of being manufactured using other materials, such as, e.g.,tungsten. Alternatively, another material may be added to the primarymaterial used to manufacture the disk.

[0097] An array of capillary x-ray optic lenses 71 preferably is alignedwith an array of radiation sources/focal spots 72(a) that projectmultiple electron beams incident to a rotating cylindrical anode to forman extended slit-like radiation beam generated by an extended radiationsource. This configuration allows the radiation to be focused into theextended slit radiation beam. As discussed, the composite cylindricalanode 73 shown in FIG. 7c preferably is comprised of rhodium disks 74and molybdenum disks 75. Shifting the tube laterally by one disk widthwhile maintaining the positions of the focal spots 72 and capillaryx-ray lens array 71 permits the selection of a specific anode spectrum.In the configuration shown in FIG. 7c, the choice is between a spectrumgenerated by the rhodium disks 74 and a spectrum generated by themolybdenum disks 75. Coolant 76 is passed through the anode 73 in orderto facilitate the maintenance of an optimal operating temperature.

[0098] Other composite anode tube geometries are possible. For example,an anode could be built by combining 2 or more fractional, includinghalf or quarter, circle cylinders. FIG. 7d illustrates an oscillatingcomposite anode 79 comprised of two materials, each in the shape of afractional circle cylinder. A plurality of focal spots 72(b) is locatedlongitudinally on each fractional cylinder 77, 78. Two materials thatare capable of being used to manufacture the fractional cylinders 77, 78include rhodium and molybdenum. The configuration shown in FIG. 7d, asthe configuration in FIG. 7c, allows for a choice of spectrums generatedby the materials comprising the oscillating composite anode 79.

[0099] Another alternative geometry is evidenced in a continuous slitscan acquisition format. In a continuous slit scan acquisition format,the anode would oscillate through an arc slightly smaller than thefraction of a circle which the desired material, such as molybdenum,rhodium, or tungsten, occupies. In this case only a single material isused to determine the x-ray spectrum distribution.

[0100] Another alternative embodiment uses at least two full-sized anodecylinders comprised of different materials which can be shifted in andout of position so that the same electron beam source can be used. Onlythe anode that is being used to generate x-rays needs to rotate. Thisparticular multiple-anode configuration is used so that the x-ray tubeunit will remain reasonably compact.

[0101] Yet another alternative embodiment is to abut different anddistinct anodes such that a single elongated anode is present. With thisembodiment, an entire anode can be shifted depending on which anodematerial is desired.

[0102] This approach can be extended to the deployment of multiplefocusing capillary x-ray lenses so that multiple slits or slots can bescanned at the same time using a single x-ray tube focal spot. Adrawback to the use of a capillary lens to focus a small focal spot ontoan extended slit is that the capillary x-ray optics will become morecomplex in order to direct radiation, in an approximately paralleldirection, to sections of the slit which are far from the center of theslit. The capillary x-ray lens design can be simplified if the focalspot source or radiation source is reshaped to more closely match theshape of the slit or slot. The x-ray source can be modified such thatadditional focal spots are incorporated parallel to the length of theslit. An equal number of capillary x-ray lenses or a lens array withrelaxed design constraints are abutted and aligned with thecorresponding focal spots in the focal spot array of a rotatingcylindrical anode x-ray tube.

[0103] Compression Plates

[0104] It should be noted that the use of compression plates to compressthe area of the subject being imaged may be desirable. A reasonablysmall tissue path between the radiation source and the detector deviceis highly desirable in both nuclear medicine scintimammography and x-raymammography. This reduces absorption, scatter, and in general improvesimage quality. In scintimammography partial, i.e., limited, breastcompression can be used, allowing the detector device to move a fewcentimeters closer to a potential tumor. By comparison, more-strenuouscompression is applied in standard x-ray mammography since the breast isunder tension for a much shorter period of time. The sensitivity andspecificity of scintimammography can be improved by using theinformation acquired in the initial scan to re-image suspicious regions.Re-imaging involves applying increased compression to a smaller sectionof the breast using contoured or flat compression plates of reducedarea. Contoured and flat compression plates of reduced area, includingversions with an open region in the compression plate, for opticalimaging of tissue have been described by Nelson et al., U.S. Pat. No.5,999,836, filed Feb. 2, 1996, which is fully incorporated herein byreference for all it discloses and describes. In a compression platewith an open region, the open region is located adjacent to the skinsurface. This open region typically allows air and/or a couplingfluid/gel to be in contact with the skin surface. Radiation from anacoustic source can also be coupled into and out of the open region(s),enabling compression transmission and backscatter (reflection) acousticimage data and acousto-optic image data to be acquired as well asoptical image data. The size and geometry of the open region in acompression plate can be customized according to the application.

[0105] A compression plate of reduced area refers to the actual platesurface which is used to compress a section of the breast to a uniformthickness relative to the surface of a typical compression plate whichis used to compress the entire breast to a uniform thickness. Forexample, if a standard compression plate is translated with respect tothe center of the breast such that approximately 50% of the breast arecompressed uniformly, then this functions as a compression plate ofreduced area. This additional level of compression permits a detectormodule array to be positioned nearer to a potential tumor. If a hole isincluded in the compression plate even closer positioning is possiblewhile allowing other instruments, including instruments for ultrasoundimaging, for optical imaging, and for injecting materials or obtainingtissue samples, to gain access to the compressed area. In some instancesit is possible to forego the initial imaging of the entire breast andinstead begin by imaging smaller sections, which are compressed withincreased force relative to compression of the entire breast, if thetotal image acquisition time is acceptable. In this image acquisitionformat adjacent images should have sufficient overlap so that potentialstructures of interest will be visible in at least one image section.

[0106] The concept of compressing a smaller section of the breast morestrenuously than would be tolerated for whole-breast compression inscintimammography in order to achieve greater local compression can beapplied to x-ray mammography. One rather limited approach is to positionthe patient such that the left edge or right edge of a standardcompression plate, approximately 24-30 cm×18-24 cm, is near the centerline on the breast, slightly more than one-half of the breast could becompressed and scanned. A x-ray technologist would then reposition acompression plate relative to the breast such that the other half iscompressed and scanned. If higher levels of compression are desired thenone or both flat compression plates need to be reduced in size.

[0107] Contoured or flat compression plates, including plates withholes, that can compress only a section of a breast rather than theentire breast, as is practiced in x-ray film-screen mammography, mayeliminate the need or simplify the requirements for items such as x-rayoptics, multiple or extended focal spot sources, and multiple slits.X-ray tube power handling requirements could be reduced since continuousscanning occurs across a smaller area in comparison to conventionalx-ray mammography imaging even if the compressed tissue thickness wereto remain the same. Additionally, greater levels of compression can beattained if one or both of the plates of reduced size are contoured.

[0108] Turning to FIG. 10a, a perspective view of a contoured uppercompression plate 1120 that is appropriate for compressing a section ofa breast 1111 is shown with the image scan area 1123 indicated. In thisembodiment, the bottom compression plate 1121 is flat, simplifying thepositioning of the breast 1111.

[0109] In FIG. 10b, the flat bottom compression plate is replaced by asecond contoured compression plate 1122. This configuration enablesadditional compression of the breast 1111 as compared with theconfiguration illustrated in FIG. 10a.

[0110] The present invention is also directed to a method of acquiring aseries of overlapping successive sections or sub-images in order toincrease image resolution of the subject. Turning to FIG. 10c, theoverlap 1133 that is produced by acquiring successive image sections1130, 1131, 1132 of the subject are illustrated. This overlap 1133 canbe utilized to produce a continuous, higher resolution image. Theoverlap 1133 must be sufficient so that small structures 1134, 1135 maybe viewed in at least a single image area. To acquire the successiveimage sections 1130, 1131, 1132, after each section is scanned, thecompression plate or plates are repositioned relative to the breastbefore the next section is scanned. Efficient repositioning involvesmarking temporary spots on the breast or using a focused light beam onthe breast in order to define the locations of the sections to becompressed. The compression plate or plates are repositioned such that asmall overlap between adjacent sections occurs. This is continued untilthe entire breast is scanned. A series of high resolution breast sectionimages can then be evaluated by a radiologist.

[0111] Section areas should be sufficiently large such that anystructures of interest can be clearly discerned within at least onesection image. Advantages include lower patient dose and higher spatialand contrast resolution, less stress on the x-ray source, reducedscatter, and the option to use a less-energetic x-ray spectrum.Additionally, if the procedure is video recorded, the image sections canbe referenced to a video recording of the various positions of thecompression plates in order to increase the accuracy of the scans. Analternative implementation of this technique is to acquire a completescan initially and then selectively re-image problematic sections usingincreased compression.

[0112] Dynamic Acquisition of Images

[0113] The present invention is also directed to a process fordynamically acquiring partial images of a subject image in order toobtain an entire, optimized image of the subject. This method isparticularly advantageous when utilized to acquire images of a breast.The process of image optimization based on the energy spectrum andintegrated intensity while limiting patient risk is complicated by thefact that breasts are typically non-uniform in tissue composition andthe tissue distributions are non-uniform. In order to determine areasonable compromise x-ray spectrum it would be desirable to implementa static or dynamic pre-scan since both techniques permit dynamicacquisition of the mammography image. Image optimization is obtained byscanning a tissue volume that is no finer than the area of the slit orslot. A static pre-scan acquires an entire image at a low radiationlevel in order to determine the degree of attenuation while avoiding theradiation levels needed to acquire an acceptable image. After thepre-scan, the actual image is acquired based on all of the pre-scandata. In this case the tube voltage and current could be dynamicallycontrolled during image acquisition. If the tube uses an array ofradiation sources (see FIG. 7e) then individual sources or sub-arrays ofsources can be configured as needed in order to provide the desired beamcharacteristics during a scan. A dynamic pre-scan uses two slits orslots which move in parallel. The first slit or slot is used to acquirethe low radiation level data which is then used to dynamically andadaptively adjust the x-ray tube current and/or KV so that an acceptablesignal-to-noise ration (SNR) is maintained for each tissue segmentimaged by the second slit or slot.

[0114] Alternatively, the pre-scan may be avoided by adjusting theintensity, i.e., the current, and/or tube voltage dynamically(“on-the-fly”) in order to maintain an acceptable SNR. A feedback systemmanipulates beam current and/or KV. At each slit or slot position, thecurrent level is initially reduced and the detected output is analyzed.The beam current and/or tube KV is then increased to the appropriatelevel or the time the slit takes to scan a slit/slot area is increasedso as to acquire adequate statistics. Alternatively, both the beamcurrent and the scan time may be increased in order to acquirestatistics. Another, less-complex, dynamic acquisition technique is tooperate with a constant beam current and then track the time needed toacquire adequate statistics for each slit or slot area.

[0115] Single-slit and multi-slit designs are known to those skilled inthe art of x-ray radiography. The utility of such designs can beenhanced by incorporating x-ray optics with traditional or novel focalspot configurations in conjunction with efficient detector modules.Additional benefits are gained in x-ray mammography andscintimammography by modifying the scanning procedure so that increasedcompression is implemented. Preferably, compression plates such as thosedescribed above and in FIG. 10a and FIG. 10b are utilized to implementthe increased compression.

[0116] Correction and Tuning of an Array

[0117] The present invention is also directed to a novel method ofcorrecting and tuning a detector array that preferably involves trackingone or a limited number of spheres, such as microspheres, or smallcapsules, said spheres or capsules containing known levels ofradioactivity, as they are taken up by or circulate within the patient.These are collectively referred to as reference sources. Since thesizes, compositions, activities, and photon energies of the referencesources are known or are measured prior to their introduction into thepatient, the scattering and absorption effects of tissue positionedbetween these reference sources and the detector can be measureddirectly once the reference sources are at the desired locations. Thereference sources can be designed to be biodegradable or inert dependingon how long or where they are expected to be within the body. Thereference sources can have internal structures and non-uniform activitydistributions. Typically the reference sources are introduced into thepatient prior to the nuclear medicine test. The reference sources canalso function as distinct, internal, small sources that can be measuredwith little or no interference from other reference sources. Individualreference sources can have distinctive properties such as differentlevels of radioactivity, different types of radionuclides, or theincorporation of magnetic, acoustic, inductive, or x-ray attenuatingmaterials. These properties can be useful for identifying specificreference sources within the body, measuring the effects of tissue atdifferent energies, helping to guide the reference source to a desiredlocation, and providing position information by causing the referencesource to absorb, reflect, or emit acoustic, EM, or ionizing radiationwhen interrogated by an external field. The reference sources can alsobe tracked as they move within the body. Once the relatively smallreference sources are in the appropriate locations they also can be usedto fine tune and focus the detector array for that specific imagingtask. Thus, the position-dependent imaging capabilities of the detectorarray can be estimated for a patient. If the reference sources aresufficiently distinct from the radionuclides introduced into the patientduring a nuclear medicine test then estimating attenuation and focusingcan be done dynamically, permitting adaptive imaging.

[0118] The concept of adaptive imaging is utilized in many imagingapplications. In particular, the use of artificial guide-stars iswell-known in Astronomy. An important difference between our referencesource and a guide-star is that the intensity of the guide-star is notparticularly important. The guide-star is used to correct phasedistortions to an optical wavefront due to a turbulent atmosphere. Themethod of the present invention attempts to estimate attenuationcorrections and use the reference source to help focus the detectorarray at approximately the position of the actual radionuclidedistribution. The correction and tuning/focusing method along withappropriate reference sources can also used with existing Gamma cameras,PET scanners, etc.

[0119] The present invention is additionally directed to a process ofcalibrating a detector module array using a known source distribution.Electronic calibration of a detector module array involves using a knownsource distribution such that the responses of individual detectormodules can be balanced either electronically or through softwareamplification of the digitized data. This calibration effort willinclude evaluating detection events that are recorded by more than onedetector module, which is similar to the Gamma camera problem ofevaluating detection events recorded by multiple PMTs. Typical sourcedistributions include collimated spots, slits, slots, or flat fieldswith appropriate energy distributions. It is assumed that source energydistribution is appropriate for the imaging task the detector moduleswill be used for. If the detector offers energy resolution then anadditional calibration can be performed to account for energyresolution. The energy-dependent Modulation Transfer Function (MTF (E))can be measured over the expected energy range of the x-ray source orfrom a series of measurements involving narrow band sources withdifferent energies.

[0120] The process may be applied to the radiographic imagingapplication of x-ray mammography. The x-ray source properties arewell-defined. In traditional x-ray film-screen mammography using anintegrating detector, the intensity of the x-ray field decreases orfalls off as the position changes from the center to the edge of thex-ray field. The result is a divergent beam from the focal spot, saidfocal spot being a point-like x-ray source. Calibration of thisrelatively large, planar, x-ray field is typically not done. Nextconsider replacing the film-screen detector with a detector arraycomprised of a single detector module which is appropriate for slit-scanimaging. Once the detector module is aligned with respect to the x-raysource then a calibration can be performed that approximately correctsfor the variations of the x-ray beam intensity at the locations of thedetector module detector pixels. This results in a position-dependent,energy-dependent, intensity profile. For example, if the slit-likedetector module uses an edge-on detector, the intensity of the slit-likex-ray beam along the length of the detector can be measured. Thespectral distribution of a typical Mo-anode or W-anode mammography x-raytube is relatively broad band, usually greater than 10 KeV. This impliesthat the information content of detected photons at the upper and lowerextremes of the spectral band can be substantially different for thetypical x-ray energies used in film-screen mammography. If the edge-ondetector is capable of providing sufficient energy resolution, such aswhen an energy-resolving detector rather than an integrating detector isutilized, then additional information is available. Each detected photonrepresents the exponential attenuation properties of the filter, whichin the case of mammography is breast tissue. The filter, due to itsattenuation properties, modifies the local x-ray beam intensity andspectral distribution at each detector pixel. If the spectraldistribution is uniform along the length of the detector then areasonable comparison of corrected intensity and spectral contentbetween individual pixels in the detected image can be made. What isessentially acquired is a set of overlapping energy-dependent images. Ifenergy-dependent MTF (MTF (E)) measurements are available, then animproved analysis of the energy-dependent images is possible. If thespectral distribution of the source is not uniform along the length ofthe detector then the position-dependent, source spectral intensitydistribution can be measured and used to approximately correct thedetected data.

[0121] An alternative embodiment of this process involves narrowing thex-ray beam bandwidth about an appropriate energy for a particular breasttype, adjusting for size and composition. This modification simplifiesthe detection and analysis process for both integrating detectors andenergy-resolving detectors. Configurations of detectors that would beappropriate for use in this embodiment of the process are describedabove and in FIG. 5a(i)-(ii), FIG. 5b(i)-(ii) and FIGS. 7a-7 d.

[0122] It is desirable to measure the detector MTF (E) at theappropriate energy. In addition, a narrow bandwidth filter may beutilized in order to reduce patient risk by removing radiation energieswhich are totally absorbed by the breast or represent relatively littleinformation about the properties of breast tissue.

[0123] Although the embodiments of the present invention have beendescribed in terms of its use for nuclear medicine and x-ray mammographyapplications, the present invention may also be used for other medicalradiographic imaging applications as well as industrial and scientificapplications. For example, similar designs can be used with appropriateradiation collimators such as neutron mirrors or electron optics forimaging sources of neutrons or charged particles, respectively.Radiological and non-medical applications which utilize compositionanalysis based on Compton scatter measurements and/or tomographicimaging will also benefit from this design. Unconventional collimatorssuch as x-ray optic, configurable, and Compton scatter collimators canbe used with standard Gamma cameras to improve the capabilities of thesedevices.

[0124] While the invention is susceptible to various modifications andalternative forms, specific examples thereof have been shown by way ofexample in the drawings and are herein described in detail. It should beunderstood, however, that the invention is not to be limited to theparticular forms or methods disclosed, but to the contrary, theinvention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the appended claims.

What is claimed is:
 1. A radiation detector array, comprising: aplurality of radiation detector modules, wherein each module comprises:at least one radiation detector, a communication link for transferringdata between the module and a computer system.
 2. The array of claim 1further comprising: a collimator mounted on each detector whereby thecollimator is positioned on a surface of the detector facing a radiationsource, the collimator being capable of optimizing radiation detectionby the detector.
 3. The array of claim 2 wherein the detector is adetector chosen from the group consisting of a linear arraysemiconductor detector, a small, two dimensional semiconductor detector,an edge-on semiconductor detector, and an edge-on scintillator detector.4. The array of claim 2 further comprising: a radiation shieldsurrounding the array, wherein the shield is designed to reduceerroneous detection of incident radiation by the array.
 5. The array ofclaim 2 further comprising: tracks in operable connection with themodules that facilitate movement of the modules along the tracks,wherein the tracks are configured in a geometry chosen from the groupconsisting of a cylindrical geometry, a spherical geometry, and acontoured geometry.
 6. The array of claim 5 wherein the modules arecapable of moving along the tracks independently of other modules in thearray.
 7. The array of claim 2 further comprising: flexible tracks inoperable connection with the modules that facilitate movement of themodules along the tracks in a manner whereby the modules conform to anarea of a patient being monitored.
 8. The array of claim 2 wherein thecollimator is configured for increased apparent aperture of the module,for spectral filtering, and for decreased detection of scatteredphotons, the collimator being one chosen from the group consisting of anunfocused capillary collimator and a minifying capillary collimator. 9.The array of claim 2 wherein the collimator is a Compton scatter modulecollimator.
 10. The array of claim 2 further comprising a configurablex-ray optics subsystem capable of functioning as a narrow bandwidthfilter, a focusing device, and a directional filter to enhance thecollimator performance.
 11. The array of claim 10 wherein the x-rayoptics subsystem comprises a plurality of nested refractive lensesconfigured to produce multiple focused beams wherein each beam isdirected to a corresponding detector module.
 12. The array of claim 10wherein the x-ray optics subsystem is a subsystem chosen from the groupconsisting of an x-ray mirror and an array of micromirrors.
 13. Thearray of claim 10 wherein the x-ray optics subsystem comprises: a firstrefractive lens component, comprising a plurality of refractive slatsattached to a support structure, wherein the slats are configured torefract radiation towards a focal point on the module, and a secondrefractive lens component, comprising a plurality of refractive slatsattached to a support structure, wherein the slats are configured torefract radiation towards a focal point on the module, wherein the firstrefractive lens component and the second refractive lens component areoriented so that the plurality of refractive slats of the firstcomponent faces the plurality of refractive slats of the secondcomponent.
 14. The array of claim 13 wherein the first and secondrefractive lens components are nested.
 15. A wearable radiation detectorarray comprising: a shell capable of accepting and holding a detectorarray, wherein the shell is shaped in a configuration wearable by apatient, and a detector array incorporated into the shell comprised of aplurality of detector modules.
 16. The wearable array of claim 15further comprising: an open frame structure incorporated into the shellconfigured to accept and support the array, wherein the open framesubsystem allows for varied configurations of the modules within thearray.
 17. The wearable array of claim 15 wherein the array furthercomprises: a plurality of collimators associated with each module,wherein the collimators are capable of optimizing imaging of thepatient.
 18. The wearable array of claim 15 wherein the shell isconfigured in a shape chosen from the group consisting of a vest, ahelmet, a brassiere, a neck brace, a girdle, and a belt.
 19. An incidentradiation detection system, comprising: a radiation detector array,wherein the array comprises a plurality of radiation detector modules, amechanical positioning subsystem capable of aligning the modules withinthe array to optimally detect incident radiation, a monitoring subsystemto control operating parameters of the array and processing detectedradiation data from the array prior to transmitting said data to acomputer subsystem, and a computer subsystem to analyze the arrayparameters and detected radiation data, wherein the computer subsystemis further capable of processing the detected radiation data for imagereconstruction and material analysis purposes.
 20. The incidentradiation detection system of claim 19 wherein the positioning subsystemcomprises: a plurality of actuator arms, wherein a module is mounted onan arm, the arm thereby configured to move each module independently ofthe entire array.
 21. The incident radiation detection system of claim19 wherein the arrays are configured in a standard geometry or acontoured geometry.
 22. The system of claim 19 wherein the modules areadaptively positioned according to data obtained by analyzing the moduleparameter information and the detected radiation data.
 23. The system ofclaim 19 wherein the array further comprises a plurality of collimators,each collimator attached to a surface of a module that is oriented toface an incident radiation source.
 24. The system of claim 23 whereinthe collimators are capable of being adaptively controlled.
 25. Thearray of claim 19 further comprising: sensors capable of restrictingspeed of motion of the array and proximity of the array to a subject,wherein the sensors are selected from the group consisting of motionsensors, optical range sensors, acoustic range sensors, and pressuresensors.
 26. An electronically configurable collimator system,comprising: a first set of adjustable slats, a second set of adjustableslats, and a support frame designed to secure the first and second setof adjustable slats, wherein the first set of adjustable slats ispositioned along the support frame in an orientation corresponding to along edge of a detector module, and the second set of adjustable slatsis positioned along the support frame in an orientation corresponding toa short edge of a detector module.
 27. The collimator system of claim 26wherein the first and second sets of slats are capable of adjustmentindependently of each other.
 28. The collimator system of claim 26wherein the first set of adjustable slats is divided into subdivisions,each subdivision corresponding to a detector, and wherein eachsubdivision is capable of being manipulated independently of othersubdivisions.
 29. The collimator system of claim 26 wherein the secondset of adjustable slats is divided into subdivisions, each subdivisioncorresponding to a detector, and wherein each subdivision is capable ofbeing manipulated independently of other subdivisions.
 30. Thecollimator system of claim 26 wherein the first and second sets ofadjustable slates are both subdivided such that each subdivision iscapable of being manipulated independently of other subdivisions. 31.The collimator system of claim 26 further comprising: a manipulationsubsystem capable of adjusting the adjustable slats comprisingmanipulation devices taken from the group consisting of actuators,miniature motors, pulley mechanisms, electromechanical biopolymeractuators, piezo-drivers, micromachines, and screw drives.
 32. Thecollimator system of claim 26 wherein the first and second set ofadjustable slats are made of material chosen from the group consistingof photon attenuating material, reflective material, diffractivematerial, and refractive material.
 33. An x-ray radiographic imagingsystem, comprising: a rotatable gantry including an adjustable arm,wherein the arm is configured to hold an x-ray tube and an x-raydetector module, an x-ray tube positioned on the arm of the gantry,wherein the tube comprises: a radiation source, and an x-ray opticssubsystem designed to focus the radiation source, wherein the subsystemis chosen from the group consisting of a capillary x-ray lens, adiffractive x-ray structure, and an x-ray mirror, and an x-ray detectormodule positioned on the gantry and aligned with the tube.
 34. Theimaging system of claim 33 further comprising: at least one compressionplate for positioning a breast of a subject, wherein the at least oneplate is located between the x-ray tube and the x-ray detector module.35. The imaging system of claim 34 wherein at least one of thecompression plates is contoured.
 36. The imaging system of claim 34wherein at least one of the compression plates has an open regionlocated adjacent to the breast.
 37. The imaging system of claim 34further comprising: a first configurable x-ray mirror designed forspectral and directional filtering of radiation, wherein the mirror ispositioned between the x-ray tube and the compression plates.
 38. Theimaging system of claim 37 further comprising: a second configurablex-ray mirror designed for additional spectral and directional filteringof radiation after the first mirror had filtered the radiation, whereinthe second mirror is positioned between the compression plates and thex-ray detector module.
 39. The imaging system of claim 34 furthercomprising: a first collimator placed between the x-ray tube and thecompression plates, and a second collimator placed between thecompression plates and the x-ray detector module, wherein the first andsecond collimators moderate the radiation that is passed through thesubject breast, and the first and second collimators further concentratethe radiation into a narrowed geometry.
 40. The imaging system of claim33 further comprising: a second rotatable gantry that includes anadjustable arm configured to hold an x-ray tube and an x-ray detectormodule, wherein the second gantry is positioned parallel to the firstgantry, and wherein the second gantry is positioned an adjustabledistance from the first gantry, the distance being adjustable forscanning objects of different sizes, an x-ray tube positioned on the armof the second gantry, wherein the tube comprises: a radiation source,and an x-ray optics subsystem designed to focus the radiation source,wherein the subsystem is chosen from the group consisting of a capillaryx-ray lens, a diffractive x-ray structure, and an x-ray mirror, and anx-ray detector module positioned on the arm of the second gantry,wherein the module is aligned with the tube, and the module is furthercapable of detecting focused radiation emanating from the tube,
 41. Anx-ray optic system for generating focused radiation, comprising: aplurality of radiation sources sources capable of generating radiation,an anode subsystem comprised of a plurality of elements configured toenable a selection of a specific anode spectrum, and a plurality ofcapillary x-ray lenses, aligned with the plurality of radiation sources,for focusing the radiation.
 42. The optic system of claim 41 wherein theanode is a composite anode.
 43. The optic system of claim 41 wherein theplurality of anode subsystem elements is comprised of a first set ofmolybdenum disks and a second set of rhodium disks, wherein the firstset of molybdenum disks and the second set of rhodium disks arepositioned in an alternating fashion with a molybdenum disk alternatingwith a rhodium disk.
 44. The optic system of claim 41 wherein theplurality of anode subsystem elements comprises: a first semicircularcylinder of a first material, and a second semicircular cylinder of asecond material, wherein the first and second cylinders positioned inoperative contact to form a complete, circular cylinder and thematerials.
 45. The optic system of claim 44 wherein the first materialis molybdenum and the second material is rhodium.
 46. The optic systemof claim 41 wherein the plurality of anode subsystem elements iscomprised of a plurality of full-sized anode cylinders of differentmaterials, the full-sized cylinders being configured to enable shiftingof a cylinder such that only one cylinder at any one time filters theradiation.
 47. The optic system of claim 46 wherein the cylinders areconfigured end to end by abutting the cylinders.
 48. An x-ray opticsystem designed to generate a slit-like radiation beam, comprising: adense array of radiation sources for generating a radiation beam, and awedge-shaped capillary x-ray optic lens aligned with the radiationsources for focusing the beam into a slit-like shape.
 49. A method forimproved mammography radiographic imaging comprising: providing aradiation source that is directed towards a subject breast, providing aradiation detector apparatus to measure incident radiation from thebreast, measuring successive, overlapping subimages of the breast, andconstructing a mammography image by forming a continuous image of thebreast using the successive, overlapping subimages.
 50. The method ofclaim 49 further comprising: compressing individual sections of thebreast, measuring each individual section non-concurrently, andenhancing the entire image of the breast by supplementing the entireimage with the individual, non-concurrent measurements.
 51. A method fordynamically acquiring an optimized mammography image comprising:acquiring x-ray statistics on an area to be imaged, determining suitablex-ray beam parameters for the area to be imaged by analyzing the x-raystatistics, and adjusting an x-ray beam according to the determinedparameters.
 52. The method of claim 51 wherein a first scan performs theacquiring x-ray statistics step and further comprising: imaging the areausing a second scan to form the optimized image.
 53. A method for tuninga radiation detection apparatus by estimating the effects of tissueattenuation, comprising: introducing at least one reference source intoa subject, wherein the source exhibits a known shape, size, composition,activity distribution, and photon energy spectrum, measuring radiationscattering effects of tissue positioned between the source and aradiation detection apparatus, said measuring occurring when the sourceis at a desired location, measuring radiation absorption effects oftissue positioned between the source and the radiation detectionapparatus, said measuring occurring when the source is at a desiredlocation, and tuning the radiation detection apparatus based upon themeasured scattering effects and the measured absorption effects.
 54. Themethod of claim 53 wherein the source expresses at least one additionalproperty selected from the group consisting of magnetic, acoustic,inductive, and x-ray attenuating, said detection apparatus furthercapable of measuring the additional property.
 55. The method of claim 53further comprising: calibrating a detector array based upon the measuredradiation scattering effects and the measured radiation absorptioneffects, wherein the calibrating enables dynamic, adaptive imaging, andfocusing the detector array at an approximate location of a radionuclidedistribution based upon the calibrating.
 56. The method of claim 53further comprising: measuring an energy-dependent modulation transferfunction of the detection apparatus.
 57. A method of calibrating aradiation detection system comprising: providing a known radiationsource distribution that emits radiation, wherein the source is chosenfrom the group consisting of a uniform point-like source, a line-likesource, a spherical source, a rod-like source, a collimated spot source,a slit source, a slot source, a grid pattern source, a planar floodfield, and a shaped three-dimensional flood field, measuring the levelof radiation emitted from the source that is detected by the detectionsystem, and calibrating the detection system by evaluating the detectedradiation and balancing the system based upon the detected radiation.58. The method of claim 57 further comprising: measuring anenergy-dependent modulation transfer function of the detection system,and calibrating the system by accounting for both the detected radiationand the energy-dependent modulation transfer function.
 59. A method ofestimating the effects of tissue attenuation on the intensity and energydistribution of a x-ray beam comprising: calibrating an energy-resolvingdetector array by determining its energy-dependent modulator transferfunction, aligning the calibrated energy-resolving detector array withthe x-ray beam, measuring a first position-dependent, energy-dependentintensity profile of the x-ray beam at the detector array, transmittingthe beam through a patient, measuring a second position-dependent,energy-dependent intensity profile of the x-ray beam at the detectorarray immediately after the beam has been transmitted through thepatient, and comparing the first and the second position-dependent,energy-dependent intensity profiles of the beam.